In recent years, as the numbers of atopic dermatitis patients have increased, it has become known that the balance of the distribution of bacteria on the rough skin of an atopic dermatitis patient is disturbed. The harmless Staphylococcus epidermidis is the principal bacteria that always exists on the skin of healthy person. However, the harmful Staphylococcus aureus exists with S.epidermidis on the skin of the atopic dermatitis patient, such that the balance of the distribution of the bacteria on the skin deviates from the normal. It is also known that the symptom worsen with an increase of S.aureus. Therefore, conventionally, an external preparation for application to the skin for the treatment of atopic dermatitis contains an antibacterial agent to sterilize this harmful S.aureus.
Usually, however, when the antibacterial agent is applied to the skin of the atopic dermatitis patient, the harmless S.epidermidis is sterilized too. This result is not desirable, because the S.epidermidis on the skin prevents pathogenic microorganisms from fixing on to and invading the skin. Furthermore, because the distribution of bacteria on the skin becomes unnaturally skewed, the balance of the distribution of bacteria on the skin is disturbed all the more. These have negative effects on atopic dermatitis. For that reason, the conventional antibacterial treatment may not prove effective. Also, the numbers of harmless S.epidermidis decrease due to repetition of the conventional treatment. Accordingly, conventional antibacterial treatments for atopic dermatitis tend to gradually allow other harmful bacteria to easily fix on the skin and invade the skin.